1. Field of the Invention
The present invention relates to a set volume control device for an on-vehicle audio system capable of automatically controlling a set volume of the audio system according to vehicle speed.
2. Description of the Related Art
Japanese Patent Application Laid-open No. 2002-362241 discloses an on-vehicle audio system capable of automatically controlling a set volume of the audio system according to vehicle speed.
In this conventional device, the set volume of the audio system is automatically increased as the vehicle speed increases and is decreased as the vehicle speed decreases in order to keep sound of the audio system sufficiently audible even if traveling noise increases when running at high speed. Therefore, there are problems as follows: depending on the set volume before changing the vehicle speed, the volume becomes unnecessarily high or low after changing the speed, so that a vehicle occupant feels uncomfortable; if the volume of the audio system becomes unnecessarily high when stopping or running at low speed, thereby hindering comfortable listening; and power of a battery is wastefully consumed.